Patterns of structural change in DNA during tissue necrosis indicated by benzoylated DEAE-cellulose chromatography

Abstract

Structural change in liver DNA, isolated following administration of a necrogenic dose of carbon tetrachloride to rats, was examined by benzoylated DEAE-cellulose (BD-cellulose) chromatography. Greatest increase in the amount of DNA exhibiting single stranded character was detected 48 h after treatment, at which time massive necrosis was evident histologically. By 72 h after dosing, normal hepatic architecture had been restored and gross structural change in DNA could no longer be detected. The extent of single stranded regions in DNA isolated at various times after carbon tetrachloride intoxication was assessed by caffeine gradient elution of respective samples from BD-cellulose. By this criterion, structural damage to DNA was again most marked 48 h after treatment at which time single stranded regions extending over several kilobases were apparent. At earlier times such lesions were considerably shorter. Single stranded regions of discrete length detected 72 h after administration of the hepatotoxin appeared to be associated with cell division. Structural damage to DNA coincident with toxic injury was further characterized using BD-cellulose, by caffeine gradient elution of preparations subjected to denaturation before chromatography. The data indicate that production of single stranded regions is a major feature of DNA degradation during tissue necrosis. Whilst such degradation might otherwise confound interpretation of structural analyses based only upon strand breakage, the size of these regions suggests a basis for distinguishing between them and lesions specifically associated with repair, replication and transcription of DNA.